Electronic speed governor for a turbine

ABSTRACT

An improved electronic speed governor for a turbine wherein the speed of the turbine is controlled by the output of a pneumatic transducer and wherein the pneumatic transducer includes a hollow housing having enclosed therein the entire circuitry for the electronic speed governor.

United States Patent 1191 1111 3,834,830

Johncock Sept. 10, 1974 15 ELECTRONIC SPEED GOVERNOR FOR A 3,572,9583/1971 Jensen 415/17 TURBINE 3,578,871 5/1971 Sakamoto....... 415/3,698,829 10/1972 Kubo et al. 415/36 [75] Inventor: Allan W. Johncock,Texas City, Tex. 3,741,246 6/1973 Braytenbatt 415/17 A Sta d dOilC Ch,lll. [73] lSSlgflee n ar omp yt 1 ago Primary ExaminerC. J. HusarFiled: 1973 Attorney, Agent, or Firm-Hume, Clement, Brinks, [21] Appl.No.: 339,533 Willian, Olds & Cook, Ltd.

52 us. c1 415/30, 415/40, 415/17 1 APSTRACT [51] Int. Cl. F0lb 25/06 AnImproved electronic Speed g'ovemof for a tufbme [5 Field f a h 415 20 23 40 wherein the speed of the turbine is controlled by the 43 15 17output of a pneumatic transducer and wherein the pneumatic transducerincludes a hollow housing hav- 5 References Cited ing enclosed thereinthe entire circuitry for the elec- UNITED STATES PATENTS Speed gmemm-3,340,883 9/1967 11 Claims, 10 Drawing Figures Petemel 4l5/l5 2 REMOVECONTROL SET POINT SPEED INDICATOR GAIN RESET sET-PomT CONTROL co TROLconmor cmcun' ADJUSTABLE FEEDBACK ONE'SHO sum/um; CONTROL T JUNCTI AMULTI- FILTER MP VIBRATOR 1 ,0

so i 26 2 I 94 CONTROL I TO AIR CURRENT I TRANS- AMP TURBINE DUCERCONTROL VALVE I6 /0 TURBINE PATENTEU SEP 1 0:914

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F IG. IO 1| /26 To SPEED VOLTAGE EXTERNAL OF AMP,44 A20 INDICATORSELECTRONIC SPEEDGOVERNOR FOR A TURBINE BACKGROUND OF THE INVENTION Thepresent invention relates to a control device for electronicallycontrolling the speed of a turbine and more particularly, for animproved electronic speed governor for a turbine wherein the electronicelements of the speed governor are self-contained within a housing of apneumatic transducer.

In recent years, the trend has been to use electrical, rather thanmechanical devices for controlling the speed of a turbine. Two suchelectrical devices are disclosed in US. Pat. No. 3,578,871, issued toTetsuzo Sakamoto on May 18, 1971, and in US. Pat. No. 3,340,883, issuedto J. R. Peternel on Sept. 12, 1967.

Although the electronic devices disclosed in the above two identifiedUnited States patents have served the purpose, they have not providedentirely satisfactory under all conditions of service in that theelectronic circuitry of the speed governor was housed externally of theelectromechanical transducer which was used to directly control thespeed of the turbine and was thus subjected to a corrosive environmentand could possibly overheat. Applicants invention overcomes thesedifficulties.

SUMMARY OF THE INVENTION The general purpose of this invention is toprovide an improved electronic speed governor for a turbine whichembraces all of the advantages of similarly employed speed governors,which is economical to produce and which is not susceptible to corrosiveelements or overheating.

To attain this, the present invention contemplates and utilizes adigital signal generating means associated with the turbine to producean electrical signal which is a function of the rotational speed of theturbine. A first platform'is located within the housing of a current toair or a pneumatic transducer. Located on the first platform is a meansfor converting the digital signal into a D. C. voltage velocity signalwhich is proportional to the speed of the turbine. A referencegenerating circuit is also located on the first platform for generatinga preselectable reference voltage signal indicative of a desired speedof the turbine. A comparator circuit located on the first platformcompares the velocity signal with the reference voltage signal andgenerates an error signal indicative of the difference between thevoltage velocity signal and the reference voltage signal. Lastly, acontrol amplifier located on the first platform gener ates a controlsignal, responsive to the error signal, to the transducer whereby thetransducer in response to the control signal generates a pneumaticsignal which controls the speed of the turbine.

An object of the present invention is to provide an improved electronicspeed governor where the entire circuitry of the speed governor iscontained within the housing of an electro-pneumatic transducer.

Another object is to providean electronic speedgovernor which isrelatively protected from steam deposits and other corrosive affects.

A further object is the provision of an electronic speed governor for aturbine which isextremely simple to install and which is compact andmountable at the turbine itself.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of theelectronic speed governor.

FIG. 2 is a perspective diagram of an electropneumatic or current to airtransducer with the top portion of the housing removed showing theelectronic speed governor circuit of the present invention.

FIG. 3 is a schematic diagram of the electronic speed governor whichconstitutes a preferred embodiment of the invention.

FIG. 4 is a simplified schematic diagram of the multivibrator circuitshown in FIG. 1.

FIG. 5 is a simplified schematic diagram of the filter circuit shown inFIG. I. 1

FIG. 6 is a simplified schematic diagram showing the summing junction,the control amplifier, and the current amplifier of FIG. 1.

FIG. 7-is a simplified schematic diagram of the power supply circuitutilized in the preferred embodiment of the invention. i

FIG. 8 is a schematic diagram of additional circuitry which may be usedin combination with the electronic speed governor shown in FIG. 3.

FIG. 9 is a simplified schematic view of a portion of the circuit shownin FIG. 8.

FIG. 10 is a simplified schematic view of a portion of the circuit shownin FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingswherein like reference characters designate like or corresponding partsthroughout the several views, there is shown in FIG. 1, an electronicspeed governor circuit 10 which is used to control the speed of aturbine 12 by regulating a turbine control valve 16 through the use ofair pressure from a current to air transducer 90. The electronic speedgovernor circuit 10 is designed to be mounted at the turbine 12 throughthe uniqueness of its integral packaging within the housing of thecurrent to air transducer used to supply the air pressure to the controlvalve 16.

A speed detector 18 is provided to sense the speed of the turbine shaft14. One conventional speed detector 18 comprises a wheel 20 having aplurality of teeth 22 which is mounted on the turbine shaft. A magneticpick-up head 24 is provided which produces a plurality of pulses thefrequency of which is directly related to the speed of the turbine shaft14. These pulses form a digital signal whose frequency is a function ofthe rotational speed of the turbine shaft. The digital pulses aretransmitted to a mono-stable or one shot multivibrator 30. Themulti-vibrator 30 and filter 42 convert the pulses into a D. C. voltagewhich is'proportional to the speed of the turbine. The filter circuit42also provides buffering and scaling of the voltage velocity sig nal.The voltage velocity signal is then transmitted toa summing junction 52.Also present at the input of the summing junction 52 is a referencevoltage signal which is generated by a set point control circuit 66. Thereference voltage signal generated by the set point control circuit 66is preselectable and is indicative of the desired speed of the turbine.

Both the reference voltage signal from the set point control circuit 66and the D. C. voltage velocity signal from the filter 42 are compared atthe summing junction 52 and are transmitted to a control amplifier 70.If a difference exists, an error signal is produced at the output of thecontrol amplifier 70. Thus, the actual velocity of the turbine isconstantly being compared to the desired velocity as determined by theset point control circuit 66. The control amplifier 70 functions as anoperational integrator that integrates the error signal and thusprovides a smoothly modulated control voltage which is then transmittedto a current amplifier 80 where the voltage is converted into a currentwhich is then used to drive a current to air transducer 90. The currentto air transducer 90 is a conventional pneumatic transducer wherein apneumatic output is obtained from a current input. The pneumatic outputfrom the current to air transducer 90 is transmitted via a conduit 94 tothe turbine control valve 16 and thus adjusts the speed of the turbine12 in proportion to the amount of current from the current amplifier 80which in turn is responsive to the error signal generated from thesumming junction 52.

In the preferred embodiment of the invention, each of the componentsshown in FIG. 1 which comprise the electronic speed governor circuitwith the exception of the speed detector 18, are located within thehousing 91 of the current to air transducer 90. This can be seen in FIG.2. By placing these components within the housing, the components arecontinuously cooled and purged due to the continuous air bleeds throughthe transducer housing 91. This increases the component life incorrosive atmospheres and as such has been proven to be a greatadvantage over those systems wherein electronic components are externalto the housing of the current to air transducer. In the preferredembodiment of the invention, the current to air transducer comprises aFisher Model No. 546 transducer manufactured by the Fisher GovernorCompany. It will be recognized, however, that other similar transducersmay be utilized.

Referring to FIG. 2, the current to air transducer 90 comprises ahousing 91 within which is placed a first platform 96. Located on thefirst platform 96 are the solid state elements which comprise the oneshot multivibrator 30, the filter 42, the summing junction 52, thecontrol amplifier 70, the current amplifier 80 and the set point controlcircuit 66. As will be explained in detail below, a second platform 98may also be provided either above or below the first platform 96. Thepurpose of the second platform 98 is to house additional elements whichmay optionally be utilized with the electronic speed governor circuit10. These elements are shown in FIGS. 8l0 and will be explained below.

The current to air transducer 90 is a conventional transducer with theexception of the platforms 96 and 98 which have been added. The currentto air transducer 90 converts a current input which in the preferredembodiment of the invention comes from the control amplifier 80 locatedwithin the housing 91 and produces a proportional pneumatic outputthrough an outlet pneumatic tube 94. In addition, a source of air supply92 is also provided for the transducer. The transducer in thepreferredembodiment may be mounted in the vicinity of the turbine which is to becontrolled. Only two external wires are necessary to connect the currentto air transducer 90 to the entire system. One such lead is designatedby the numeral 25 and connects the speed detector 18 to the one shotmulti-vibrator 30 located within the housing 91 of the current to airtransducer 90. A second lead 27 connects the circuitry of the electronicspeed governor 10 to a source of D. C. voltage. In the preferredembodiment, this is a 48 volt source. The 48 volts may be obtainedthrough the use of a voltage regulator from a normally available 129volt D. C. source located at the turbine.

Referring now to FIGS. 3-7, the detailed circuitry of the electronicgovernor circuit 10 will be explained. FIG. 3 shows the over-allschematic diagram of the electronic speed governor circuit 10 whichconstitutes the preferred embodiment of the invention. FIGS. 4-7 showsimplified diagramatic schematic views corresponding to some of theblock diagrams shown in FIG. 1. Referring to FIGS. 1, 3 and 4, themonostable multivibrator 30 comprises a conventional multi-vibratorwhich is triggered by the positive half cycle of the input pulses fromthe speed detector 18. These pulses are transmitted to themulti-vibrator 30 via the leads 25. The multi-vibrator 30 comprises twotransistors 31 and 32 which are triggered by the positive half cycleinput pulses from the speed detector 18. A pair of diodes 33 and 34protect the transistor 31 from damage during the negative half cycle.Triggering will not take place until the input voltage exceeds theforward biasing voltage of the diode 34 and the transistor 31 which inthe preferred embodiment is 1.2 volts. This provides immunity to noise,transients, etc. The output of the multivibrator 30 appears at thecollector of the transistor 32 and is a positive going square wave whoseamplitude is controlled by a zener diode 35. The period of the squarewave is determined by the time constant of the resistor 37 and thecapacitor 36. The capacitor 36 may be a stable silva-mica type capacitorwhich is selected based upon the RPMs of the turbine shaft and thenumber of teeth 22 on the pick-up wheel 20. Because the area under eachpulse is fixed and the frequency of pulses is determined by the turbinespeed, filtering of this square wave will produce a D. C. voltage whichis proportional to the speed or velocity of the turbine and thus formsan analog voltage signal.

The filter circuit 42 is shown in schematic form in FIGS. 3 and 5.Filtering of the square wave input from the one shot multi-vibratorcircuit 30 is accomplished by the RC network comprising resistors 45 and46 and a capacitor 47 as well as an amplifier 44 which provides acapacitor feedback through the capacitor 48 and thus provides reducedgain at higher frequencies. The amplifier 44 forms in the preferredembodiment a portion of an integrated circuit chip. It will berecognized, however, that any suitable amplifier may be utilized. Theamplifier 44 also provides buffering and scaling of the speed voltagefor application to the summing junction 52. Lastly, the amplifier 44also inverts the speed voltage signal to produce a negative signal whichis compared with a positive signal generated by the point set controlcircuit 66.

The signal generated by the set point control circuit 66 isrepresentative of the desired speed of the turbine and is referred to asthe reference velocity voltage signal. The set point control circuit 66is shown in greater detail in FIG. 3. The reference voltagerepresentative of the desired velocity of the turbine is set by varyingthe wiper associated with the resistor 69.

The negative speed signal, or in other words, the D. C. voltage signalindicative of the actual speed of the turbine, is applied through aresistor 50 to a summing junction 52 shown in FIGS. 3 and 6. At thesumming junction 52, this signal is summed with the positive signaldelivered through a resistor 49 from a set point control circuit 66. Theset point control circuit 66 is supplied with a highly stable positivevoltage from a temperature compensated zener diode 67 via a resistor 68.If the turbine is running at the set speed, the voltage produced at thesumming junction 52 will be zero. Any deviation from the desired speedwill tend to produce an error voltage at the summing junction 52. Thiserror voltage will be negative if the speed is too high and positive ifthe speed is too low. The summing junction 52 is the input to thecontrol amplifier 70.

The control amplifier 70 is a conventional amplifier and in thepreferred embodiment is shown in FIG. 3, constitutes a portion of anintegrated circuit chip common with the amplifier 44. Feedback from theamplifier 70 is provided over the feedback path 72 via the capacitor 73.This feedback is also summed at the summing junction 52. The amplifier70 therefore has a proportional signal plus an integral feedback signalat the output current stage of a transistor 82. The voltage drop acrossthe resistor 76 in the emitter circuit of the transistor 82 is used as ameasure of the current output and will produce in the preferredembodiment 1 volt at milliamps minimum output and 5 volts at 50milliamps maximum output. This voltage is applied across the gaincontrol resistor 74 where all or part of it is sent back via theresistor 75 in the capacitor 73 to the summing junction 52. The resistor75 in series with the ca pacitor 73 controls the reset action of thecontroller by controlling the charging rate of the capacitor 73. Theresistor 75 also affects the gain of the amplifier 70. The error signalgenerated by the amplifier 70 is an integral function of the errorsignal as well as a proportional function of the error signal. Thissignal then is transmitted to the control current amplifier 80 whichcomprises a transistor 82 and the associated biasing circuitry. Theoutput from the transistor 82 converts the error voltage into a currentsignal which is proportional to the error voltage. This current orcontrol signal then is transmitted via the lead 26 to the current to airtransducer 90. The current to air transducer 90 then emits a controlledair pressure via the conduit 94 (FIG. 2) which in turn regulates thevalve 16 associated with the turbine 12 thereby controlling the speed ofthe turbine 12.

In practice, the voltage at the summing junction will always be zerosince the amplifier 70 will change its output to maintain the voltage atzero. The changing output thereby manipulates the valve 16 at theturbine until the error is once again zero at which point theoutput willcease to change.

The power supply circuit 102 for the electronic speed control circuit 10is shown more clearly in FIG. 7. Poweris supplied by an internal systemlocated within the housing 91 of the current to air transducer 90. A D.C. source, conventionally 129 volts, is present at the turbine andthrough appropriate voltage reducing circuitry, is converted into a 48volt supply (not shown). The 48 volts is then applied through theresistor 103 and the zener diodes 104 and 105. A diode 106 preventsdamage by reversing the supply voltage and a zener diode 107 provides anine volt reference supply.

As mentioned previously, all of the components shown in FIG. 3 may beplaced in modular form, on the platform 96 located within the housing 91of the current to air transducer 90. By placing these components on theplatform 96 within the housing 91, the constant air bleed of the currentto air transducer will purge the electronic component of all corrosiveelements and will tend to cool them thereby ext-ending their life andextending the life of the speed governor.

Referring now to FIGS. 8-10, certain optional features are shown whichmay be added to the previously described electronic speed governorcircuit 10. These additional options may be individually added, or allof them may be added. One of these features provides for a remote speedread-out of the actual speed of the turbine 12. The second featureallows for a remote control setting of the speed of the turbine. Asmentioned previously, a voltage is present in FIG. 3' which isrepresentative of the turbine speed. To obtain a read-out, it is onlynecessary to condition this voltage to some useable level. It isapparent that a positive voltage can be inserted in lieu of the voltageacross the resistor 69 in order to vary the speed of the turbine. Ifthis voltage were derived from some standard source, such as acontroller, then it must be altered to equal this voltage speed presentat the speed desired. This would then enable a remote speed control.

Referring to FIGS. 8 and 9, the remote speed set control will beexplained. FIG. 9 shows a remote set point control circuit 86 whichcomprises an amplifier 130. The amplifier accepts an input from a pairof diodes 131 and 132. These diodes form a high signal selector betweenthe two inputs. In this instance, only the highest voltage will be theinput to the amplifier. This is done so that if both local and remoteset points are used, only the one calling for the highest speed will beselected. The local set point is developed by a single turn controlresistor which will be mounted externally to the housing of thetransducer 90 and will provide 1 to 5 volts to the amplifier 131. Thisvoltage is applied from the resistors 133 and 134 (FIG. 8).

A similar --1 to -5 volts is developed by dropping the ten to fiftymilliamps remote set signal across resistor 135. This voltage isjumpered externally to the diode 132 as shown by the dotted line inFIG.9. The amplifier 130 has gained an offset adjustment through the useof the resistors 136 and 137 which allow the incoming l to 5 volts to beconverted to any desired positive voltage span. This span willcorrespond to the speed voltage span present at the output of theamplifier 44 (FIGS. 3 and 5) over the desired variable speed range. Theoutput of the amplifier 130 is effectively the junction 138 of theresistor 139 and 140 which form an out put voltage divider. Diodes 141and 142 limit the possible output from the amplifier 130 to the voltageset by the resistor 143. This prevents a remote set point current higherthan fifty milliamps calling for a speed higher than the normal maximumspeed. The value of the resistor 143 is adjusted to achieve this limit.The diodes 144 and 145 form a high selectorwhich prevents the outputfrom falling below a desiredlevel. This Q in- ELEMENT NUMBER sures thatthe remote set point control 86 cannot slow the turbine down below thenormal minimum which is set by the resistor 146. If the remote speedcontrol circuit 86 is utilized, the resistor 60 (FIG. 3) of the localset point control circuit 66 is not utilized and is omitted. Theutilization of the remote set point control circuit 86 allows the speedof the turbine to be controlled remotely from the turbine but it is tobe recognized that if this remote feature is not desired, speed controlmay be obtained by merely using the set point control circuit 66 locatedat the housing of the transducer 90.

Referring to FIGS. 8 and 10, the remote seed readout circuit will bedescribed. The remote speed readout circuit 88 allows for a means ofreading the voltage at the output of the amplifier 44 (FIGS. 3 and 5which is representative of the speed of the turbine. This voltage isapplied via the resistor 120 to an amplifier 122. The amplifier 122forms a current amplifier having the gain set by the resistor 120.Adjustment of the resistor 120 allows calibration to any speed desired.Because the output of the amplifier 44 is controlled, any number ofread-out indicators may be connected in series, thus giving a reading ofthe actual turbine speed.

It will be noted, in FIGS. 3 and 8, that several connection points 114through 118 are provided. These connection points schematically depictthe interconnection between the circuitry of FIG. 3 and the optionalcircuitry shown in FIG. 8. In the preferred embodiment of the invention,the circuitry of FIG. 8 is placed on a second platform 98 located withinthe housing of the current to air transducer 90. This platform may bephysically above or below the first platform 96 described previously.However, if it is desired, components shown in FIG. 8 may also beapplied to the platform 96 rather than introducing a second platform 98.

It will be recognized that the schematic diagrams shown in FIGS. 3 and 8represent one illustrative embodiment of the invention. The variouscircuit elements are tabulated below as to value or type number. It willbe recognized, however, that these values are exemplary and are merelyillustrative of the invention, and various modifications may be madewithout departing from the spirit and the scope of the invention. Allcapacitors values are in micro-farads except as otherwise noted. Allresistor values are in ohms except as otherwise noted.

VALUE OR TYPE NUMBER 32, 34 Motorola MPS-65 I 5 82 2N I487 I06 IN4003I04 IN4744A 35, 67 IN939B I07 IN4736A I05 IN5352 36 5% silva micaselected for frequency 48 .0!

I08, Ill I 44 and 70 combined Motorola M I458L 38. 39 2.0K

40, 45, 47, 68 IOK -Continued ELEMENT NUMBER VALUE OR TYPE NUMBER 1 I0806 I03 400 76 100 Fisher 546 l0-50 Ma input 3- I 5 PSIG output I22 andI30 combined Motorola MCI458L Obviously, many modifications andvariations of the present invention are possible in light of the aboveteachings without departing from the spirit and scope of the inventionas set forth in the appended claims.

What is claimed is:

1. An electronic speed governor for a turbine wherein the speed of theturbine is controllable by a pneumatically controlled valve, comprising:

digital signal generating means for producing an electrical signal whichis a function of the rotational speed of said turbine;

means for converting said digital signal into a D. C.

voltage velocity signal which is proportional to the speed of theturbine;

reference generating means for generating a preselectable referencevoltage signal indicative of a desired speed of said turbine;

comparison means for comparing said velocity signal to said referencevoltage signal and for generating an error signal indicative of thedifference between said voltage velocity signal and said referencevoltage signal;

control signal generating means responsive to said error signal forgenerating a control signal; and

a transducer means having a housing wherein said transducer meansgenerates a pneumatic signal to said controlled valve in response tosaid control signal thereby controlling the speed of said turbine andwherein said converting means, said reference generating means, saidcomparison means, and said control signal means are located within saidtransducer housing whereby said air within said transducer housingprevents corrosion and reduces heating of said electronic elements.

2. The electronic speed governor of claim 1 wherein said control signalcomprises a time integral function of said error signal.

3. The electronic speed governor of claim 1 wherein said control signalcomprises a proportional function of said error signal.

4. The electronic speed governor of claim 1 wherein said control signalcomprises a proportional function plus a time integral function of saiderror signal.

5. The electronic speed governor of claim 1 further comprising anindicator means, a portion of which is located within said transducerhousing, for providing an instantaneous readout of said turbine speed.

6. The electronic speed governor of claim 1 wherein said referencevoltage signal generating means comprises a means for remotely selectingsaid reference voltage signal.

7. An improved electronic speed governor for a turbine wherein the speedof the turbine is controlled by the output from a pneumatic transducerand wherein said pneumatic transducer includes a hollow housing, theimprovement comprising:

digital signal generating means associated with said turbine forproducing an electrical signal which is a function of the rotationalspeed of said turbine;

reference voltage signal and generating an error signal indicative ofthe difference between said voltage velocity signal and said referencevoltage signal; and

control signal generating means located on said first platform means andresponsive to said error signal for generating a control signal to saidtransducer means whereby said transducer means in response to saidcontrol signal generates a pneumatic signal which controls the speed ofsaid turbine.

8. The improvement of claim 7 further comprising an indicator means forproviding an instantaneous readout of said turbine speed.

9. The improvement of claim 7 wherein said reference generating meanscomprises a means for remotely selecting said reference voltage signal.

10. The improvement of claim 8 further comprising a second platformmeans located within said housing wherein a portion of said indicatormeans is located on said second platform means.

11. The improvement of claim 9 further comprising a second platformmeans located within said housing wherein a portion of said means forremotely selecting said reference velocity voltage is located on saidsecond platform means.

1. An electronic speed governor for a turbine wherein the speed of theturbine is controllable by a pneumatically controlled valve, comprising:digital signal generating means for producing an electrical signal whichis a function of the rotational speed of said turbine; means forconverting said digital signal into a D. C. voltage velocity signalwhich is proportional to the speed of the turbine; reference generatingmeans for generating a preselectable reference voltage signal indicativeof a desired speed of said turbine; comparison means for comparing saidvelocity signal to said reference voltage signal and for generating anerror signal indicative of the difference between said voltage velocitysignal and said reference voltage signal; control signal generatingmeans responsive to said error signal for generating a control signal;and a transducer means having a housing wherein said transducer meansgenerates a pneumatic signal to said controlled valve in response tosaid control signal thereby controlling the speed of said turbine andwherein said converting means, said reference generating means, saidcomparison means, and said control signal means are located within saidtransducer housing whereby said air within said transducer housingprevents corrosion and reduces heating of said electronic elements. 2.The electronic speed governor of claim 1 wherein said control signalcomprises a time integral function of said error signal.
 3. Theelectronic speed governor of claim 1 wherein said control signalcomprises a proportional function of said error signal.
 4. Theelectronic speed governor of claim 1 wherein said control signalcomprises a proportional function plus a time integral function of saiderror signal.
 5. The electronic speed governor of claim 1 furthercomprising an indicator means, a portion of which is located within saidtransducer housing, for providing an instantaneous readout of saidturbine speed.
 6. The electronic speed governor of claim 1 wherein saidreference voltage signal generating means comprises a means for remotelyselecting said reference voltage signal.
 7. An improved electronic speedgovernor for a turbine wherein the speed of the turbine is controlled bythe output from a pneumatic transducer and wherein said pneumatictransducer includes a hollow housing, the improvement comprising:digital signal generating means associated with said turbine forproducing an electrical signal which is a function of the rotationalspeed of said turbine; a first platform means located within saidtransducer housing; a means located on said first platform means forconverting said digital signal into a D. C. voltage velocity signalwhich is proportional to the speed of the turbine; reference generatingmeans located on said first platform means for generating apreselectable Reference voltage signal indicative of a desired speed ofsaid turbine; comparison means located on said first platform means forcomparing said velocity signal to said reference voltage signal andgenerating an error signal indicative of the difference between saidvoltage velocity signal and said reference voltage signal; and controlsignal generating means located on said first platform means andresponsive to said error signal for generating a control signal to saidtransducer means whereby said transducer means in response to saidcontrol signal generates a pneumatic signal which controls the speed ofsaid turbine.
 8. The improvement of claim 7 further comprising anindicator means for providing an instantaneous readout of said turbinespeed.
 9. The improvement of claim 7 wherein said reference generatingmeans comprises a means for remotely selecting said reference voltagesignal.
 10. The improvement of claim 8 further comprising a secondplatform means located within said housing wherein a portion of saidindicator means is located on said second platform means.
 11. Theimprovement of claim 9 further comprising a second platform meanslocated within said housing wherein a portion of said means for remotelyselecting said reference velocity voltage is located on said secondplatform means.